1. Field of the Invention
The present invention relates to a liquid discharge head and a manufacturing method thereof, and more particularly, to an ink jet recording head and a manufacturing method thereof capable of performing recording by discharging ink onto a recording medium.
2. Description of the Related Art
As an application example of a liquid discharge head, there is an ink jet recording head for performing recording by discharging ink as liquid droplets onto a recording medium (generally, paper) by energy.
An example of a manufacturing method of such a liquid discharge head is disclosed in U.S. Pat. No. 7,070,912.
In the manufacturing method disclosed in U.S. Pat. No. 7,070,912, walls for a liquid flow path are provided on a substrate having energy generating elements for generating energy used to discharge liquid, an organic resin filler is placed in the flow path and on the walls of the flow path, and top surfaces of the filler and the walls of the flow path are flattened by polishing the top surfaces. Thereafter, a photosensitive resin layer is applied, and liquid discharge openings are provided in the layer.
Polishing of the organic resin filler may be performed using an apparatus for chemical mechanical polishing (hereinafter, called CMP), and the polishing is performed mainly with mechanical operations and, to a lesser extent, chemical operations.
However, there may be a case where a flat substrate surface is not achieved by the polishing. For example, since the hardnesses of the wall of the flow path and the filler are different from each other, their polishing speeds are different from each other, and uniformity of the organic resin film thickness in the silicon substrate surface cannot be sufficient. For example, in a case where a liquid discharge head is manufactured by cutting small chips from a disc-shaped wafer which is a silicon substrate, an outer peripheral portion of the disc-shaped wafer as the silicon substrate, which does not satisfy the small chip unit, is not provided with a flow path wall member. Then, the outer peripheral portion of the wafer is polished first, and there is a possibility that small chips may be obtained from the outer peripheral portion, the height of flow path wall will not be sufficiently uniform. Since the flatness of the photosensitive resin provided thereon is not sufficient, distances between the formed discharge openings and the energy generating elements are not uniform, and this may affect discharge characteristics.